[John V.]

Terry, according to the MPC Tri-Power Illustration, the 3 way Front Carb Fitting used a 9/16"-20 Plug in the LH outlet when not used.

I should not have relied on memory when I made my first post.

Seems I have forgotten a few important things.

First, the '64 GTO with A/C apparently did use a vac source (I didn't go back to check what the vac was for, possibly a valve underhood). This source was taken off the RH outlet of the Center Carb Tee, same as the big car used for the Heater.

The '64 Center Carb Tee Plug was used in numerous applications at least as far back as '59 and was a 5/16"-24 Plug.

But there was an important change for '65.

The '65 Center Carb Tee was revised. It was not the same as the '63-'64 Center Carb Tee (which in turn was different from earlier Tees). The '65 Tee was p/n 9780984.

I believe the main difference (and perhaps only difference) for the '65 Tee was a change in the RH outlet dimension.

When the RH outlet was unused, the Plug used was p/n 9780983 (note the consecutive sequencing of the Tee & Plug p/ns).

This was a 3/8"-24 Plug.

60sstuff, that Front Carb el in your pix looks to be a Threaded Sleeve Elbow. They are commercially available today but may look different. Not sure if you can find one with the correct male and female sizes.

If it was used by the Factory for Man Trans applications in '65 & '66, I was not aware of it.

Like Dick, I had thought the same Front Carb fitting (special 3 way type, maybe Dick can post a pic) was used on all Front Carbs.

In '64, this was true for sure, since all factory T-Ps used the Vac Secondary linkage.

But for '65, the special 3 way fitting is listed in the MPC for both the Tempest & Pontiac T-P with Auto Trans only (they still used the Vac Secondary linkage).

No Front Carb fitting is listed for the '65-'66 T-P with Man Trans which used the Mech Linkage and had no use for Vac off the RH side of the Front Carb.

Lucky for me, if there is a "controversy" about the correct Front Carb fitting, it doesn't involve the '64!

While nothing is listed in the MPC for the '65/'66 Front Carb fitting with Man Trans, the Threaded Sleeve Elbows are listed in Gr. 8.963 in the MPC (along with Threaded Sleeve Connectors and Nuts). The illustration is pretty close to your picture.

So what is the consensus for the '65 Front Carb Fitting with Man Trans? Simple elbow or same 3 way fitting used with the Vac Secondary linkage?

[60sstuff]

Simple elbow. Another style brass ell fitting pictured below with cap plug which was removed from a front carb base on a non P/B GTO. Although it's hard to see, an Original Family Owned red 66 that belongs to a forum member has the first design ell I posted above w/slotted plug. Then the second GTO pic I saved from an ebay auction shows the second design "block" style ell with cap plug. Pictures speak a thousand words. Nothing like 45 yr. old OEM fittings!

[Terry M. Hunt]

Can anybody provide the dimensions for the '65 tee? I understand from the discussion thus far that it is shorter than the '64. I'm guessing I will need dimensions in order to insure I get the correct piece should I locate a tee for sale. If seller is not familiar with these subtle differences, I can see how I could easily wind up with the wrong piece.

[Terry M. Hunt]

Found a reproduction in the latest on line catalog from Ames under P/N N136P. No photo available yet. Ordered one today. At $36 it better be perfect.

[frankjr8]

It will be great or send it back!

[chrisp]

Originally Posted by Terry M. Hunt

Can anybody provide the dimensions for the '65 tee? I understand from the discussion thus far that it is shorter than the '64. I'm guessing I will need dimensions in order to insure I get the correct piece should I locate a tee for sale. If seller is not familiar with these subtle differences, I can see how I could easily wind up with the wrong piece.

I have 1 i can part with 2 3/16" long x 1 1/8" wide brass with weatherhead marks , same as 60's pictured .

[Tom Vaught]

Originally Posted by John V.

So what is the consensus for the '65 Front Carb Fitting with Man Trans? Simple elbow or same 3 way fitting used with the Vac Secondary linkage?

Most of the ones I have seen for 65-66 Manual Trans were a simple elbow (not like the
64 Tee).

Tom Vaught

[Dick Boneske]

All the '64's used the tee in the front carb, as they all had vacuum linkage (some claim there were some mechanical linkage '64's, but I've never seen one). The '65/'66 manual trans (mechanical linkage) setup I've seen had the cast brass elbow in the front carb base. If no power brakes, there was a slotted steel pipe fitting acting as a plug in the elbow. Every '65/'66 automatic trans setup I've seen uses the brass tee with the power brake line plugged if no power brakes and vacuum for the throttle linkage taken off the other side of the tee.

I've attached a picture showing all the varieties of Tripower base fittings I have. The shorter tee for the center carb (distributor vaccum and heater-A/C vacuum) is next to the longer tee. The round portion with the 1/8" pipe threads is 1" long. The round portion of the longer tee is 1 11/16" long. The longer tee was used on all '64 and earlier setups I've seen. This long tee makes it awkward to attach the vacuum lines as the tee is nearly against the rear carb. The shorter tee is used on '65 setups, but '66's, I believe, used only a straight hose nipple in the base of the center carb for heater-A/C vacuum. Distributor vacuum is taken off the hollow carb stud in '66.

The odd tee is from a '64 GTO AFB. Note it uses the same slotted steel fitting to block the non-power brake port.

John V. is right about the plug for the center carb vacuum tee. There are two sizes, 3/8" and 5/16". I didn't have time tonight to sort out which is which, but believe the '64 and earlier used the smaller plug--'65 used the larger one.

Sorry for the rambling, but I've tried to provide what you're looking for.

[60sstuff]

[QUOTE=Dick Boneske;3993874] but '66's, I believe, used only a straight hose nipple in the base of the center carb for heater-A/C vacuum. Distributor vacuum is taken off the hollow carb stud in '66.

Dick - Great info (not rambling) and pics! This thread may be a little more than Terry asked for but that's why this forum is so valuable. Maybe 66 4 BBL cars used the hollow stud for dist. vacuum, but the 66 Tri-Powers got the dist. vacuum from a short straight brass nipple threaded into the center carb base as seen in the pics below. The hollow stud would have a factory black plastic cap. The exception would be the Cal. Smog Tri-Powers which used the steel line off the right front center carb body. I think the A/C vacuum in 66 came off the hollow stud.

[Terry M. Hunt]

Never too much information. I print all this stuff and keep it in a giant binder. Probably need to start a second one. Many thanks, Dick, for the photos and info. Put yourself down for a Honey Baked ham also.

[Tom Vaught]

Originally Posted by Dick Boneske

All the '64's used the tee in the front carb, as they all had vacuum linkage (some claim there were some mechanical linkage '64's, but I've never seen one).

I had to smile when I read this comment, Dick, as there was at least one mechanical linkage 64 Tri-Power that came out of Pontiac Motors and was sold to a customer.

That being said, I want to thank you, today, March 28, 2016 for all of your efforts in helping the forum members identify carb pieces, linkage pieces, and vacuum routings.

Your "Curved Linkage" 64 Mechanical Linkage (service replacement) is truly a outstanding effort to help the 64 GTO / 421 Guys go to a Mechanical Linkage on their vehicles and be correct for a show.

Tom Vaught

[t walgamuth]

Originally Posted by Tom Vaught

I had to smile when I read this comment, Dick, as there was at least one mechanical linkage 64 Tri-Power that came out of Pontiac Motors and was sold to a customer.

That being said, I want to thank you, today, March 28, 2016 for all of your efforts in helping the forum members identify carb pieces, linkage pieces, and vacuum routings.

Your "Curved Linkage" 64 Mechanical Linkage (service replacement) is truly a outstanding effort to help the 64 GTO / 421 Guys go to a Mechanical Linkage on their vehicles and be correct for a show.

Tom Vaught

So is the vac operated secondaries reliable and serviceable if brought up to snuff or should I convert it ti manual secondaries? (mechanical)

Tom Walgamuth

[Joe37]

Yes, the GTO used the same setup only mechanical linkage, '65-'66 only. '66 had a bigger center cab and matching manifold. Nothing wrong with vacuum system if its working correctly, you just have to remember that they are slower to release than mechanical linkage ( have plenty of room ahead of you ).

[60sstuff]

Originally Posted by Joe37

Nothing wrong with vacuum system if its working correctly, you just have to remember that they are slower to release than mechanical linkage ( have plenty of room ahead of you ).

Trust me, I know all about that SLOW release of WOT.

[Tom Vaught]

Originally Posted by Dick Boneske

All the '64's used the tee in the front carb, as they all had vacuum linkage (some claim there were some mechanical linkage '64's, but I've never seen one).

I have only seen two cars that I would say have a chance to be a Mechanical Linkage set-up. "From the factory production line", NO, NO, NO.
From the Pontiac Zone Office: Mine and possibly Terry Hunt's set-up but I do not know know if it was actually delivered to a Dealer, like my was (A 'Brass Hat' Vehicle).

Also mine was built with Documented serial # Parts (supplied by the Rochester carb people) directly to the Brass Hat vehicle.

So I totally agree with Dick on this one. NO production line 64 GTOs (with Mechanical Linkage) EVER went down that line.

Tom V.